1. Field of the Invention
The present invention generally relates to cover restricting mechanisms and, more particularly, to a cover restricting mechanism for a foldable electronic device such as a mobile telephone, an electronic notebook, and so on.
2. Discussion of the Related Art
With the development of the technologies of wireless communication and information processing, portable electronic devices such as mobile telephones and electronic notebooks are now in widespread use. These electronic devices enable consumers to enjoy the convenience of high technology services anytime and anywhere. Foldable electronic devices are particularly welcome by consumers for their convenience.
Generally, foldable electronic devices have most of the electronics in one housing, called the body. The other housing, called the cover, normally contains fewer electronic components than the body. Other foldable electronic devices have all the electronics in the body, with the cover containing no electronics. Various types of hinge assemblies are used to join a body and a cover of a foldable electronic device, so that the cover can unfold up from and fold down upon the body. Manufacturers are constantly seeking to reduce the volume, size, and weight of such foldable electronic devices. Also, it is desirable for the hinge assembly coupling the body with the cover to have a long working lifetime.
A modularized hinge assembly is generally used to hinge together a cover of a foldable electronic device and a body of the foldable electronic device. The hinge assembly typically includes moving parts such as a cam member having a cam surface, a cam follower having a cam follower surface, a spring, a shaft, and a housing. The cam member, the cam follower, and the spring are placed around the shaft and then received in the housing, thereby being held together in a unified structure. The housing is secured to the body, and the cam member engages with the cover. The cam member and the cam follower always contact each other by engagement of the cam and follower surfaces and due to the action of the spring. When opening the cover, the cover is rotated by hand, which makes the cam member rotate along with the cover. At the same time, the cam member urges against the cam follower, making the cam follower move along the shaft and compress the spring. When the cam member rides over a convex portion of the cam follower, the cover is opened to a predetermined angle. Releasing the cover, the cam follower urges against the cam member, under the force of the spring, and makes the cam member continuously rotate, thus making the cover open fully.
In the above-described hinge assembly, when the cover is opened to a predetermined angle, the cover rotates to a predetermined position. This rotation occurs due to the engaging relationship of the cam follower and the cam member, such engagement being maintained under the force of the spring. However, the abrupt force of the spring of the hinge assembly has a large impact on the cover, which may damage the cover and/or decrease the working lifetime of the cover. Such a negative influence on the operation of the cover would expectedly reduce the working lifetime of the foldable electronic device, overall. In addition, many foldable electronic devices need to be opened to other positions such as 150° or 160° positions. This angle requirement means that the body of the foldable electronic device itself needs to be specially designed in order to limit the maximum opening angle of the cover. This designing takes up valuable “real estate” on the body, increases the complexity of the manufacture of the body, and increases the overall volume and weight of the mobile phone. Furthermore, each time the cover is opened, it impacts the body. The body is liable to become worn or damaged due to such impact, thereby shortening the working lifetime of the mobile phone.
What is needed, therefore is to provide a cover restricting mechanism that overcomes the above-described problems.